Thin film transistor panel and liquid crystal display using the same

ABSTRACT

An LCD device includes a transmissive LCD panel assembly, a backlight assembly for supplying light to the LCD panel assembly, and a selective reflection film provided between the backlight assembly and the LCD panel assembly. A display region of the LCD has a low-resolution area and a high-resolution area, and a pixel formed in the low-resolution area that is larger than a pixel formed in the high-resolution area.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation Application of U.S. patentapplication Ser. No. 11/302,968 filed Dec. 14, 2005, which claimsbenefit to Korean Patent Application Nos. 10-2004-0105548 filed on Dec.14, 2004, Application No.: 10-2004-0109641 filed Dec. 21, 2004,Application No.: 10-2004-0115067 filed on Dec. 29, 2004 and ApplicationNo.: 2004-0117256 filed on Dec. 20, 3004, the contents of which areherein incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

(a) Technical Field

The present disclosure relates to a liquid crystal display (LCD) and athin film transistor (TFT) panel for the same.

(b) Discussion of the Related Art

Generally, an LCD includes a pair of panels respectively havingelectrodes on their inner surfaces, and a dielectric anisotropy liquidcrystal layer interposed between the panels. In the LCD, a variation ofthe voltage difference between the field generating electrodes, i.e., avariation in the strength of an electric field generated by theelectrodes, changes the transmittance of the light passing through theliquid crystal layer, and thus desired images are obtained bycontrolling the voltage difference between the electrodes.

In the LCD, the light may be a natural light or an artificial lightemitted from a light source employed in the LCD.

A backlight is a representative device for providing the artificiallight in the LCD and utilizes, for example, light emitting diodes (LEDs)or fluorescent lamps, such as cold cathode fluorescent lamps (CCFLs) andexternal electrode fluorescent lamps (EEFLs), as the light source.

Power consumption by the backlight represents a large part of the totalpower consumption of the LCD. Accordingly, to reduce power consumptionof the LCD, it is desirable to focus on raising power efficiency of thebacklight or reducing use time thereof.

Batteries used as a power source in mobile technologies, such as, forexample, portable phones, have limited power supply capacities. For thisreason, efforts have been made to increase maximum use time of themobile technologies by reducing the power consumption by LCDs employedin the mobile technologies.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a low power-consumptionLCD, and an LCD having a display region capable of displaying images atall times, regardless of the operation state of a backlight employed inthe LCD.

According to an embodiment of the present invention, a liquid crystaldisplay (LCD) device includes a low-resolution area and ahigh-resolution area, wherein a pixel formed in the low resolution areais larger than a pixel formed in the high resolution area.

This LCD device may include a transmissive LCD panel assembly, abacklight assembly for supplying light to the LCD panel assembly, and aselective reflection film provided between the backlight assembly andthe LCD panel assembly.

Preferably, the transmissive LCD panel assembly includes a thin filmtransistor (TFT) panel, a color filter panel that is opposed to the TFTpanel with a predetermined interval therebetween, a liquid crystal layerinterposed between the TFT panel and the color filter panel, and a firstpolarizer and a second polarizer that are respectively provided on outersurfaces of the TFT panel and the color filter panel.

The LCD device may further include a data driving chip mounted on theTFT panel, a first gate driving chip mounted on the TFT panel to operatethe low-resolution area, and a second gate driving chip mounted on theTFT panel to operate the high-resolution area.

Alternatively, the LCD device may further include a data driving chipmounted on the TFT panel, a first gate driving circuit formed in the TFTpanel to operate the low-resolution area, and a second gate drivingcircuit formed in the TFT panel to operate the high-resolution area.

Preferably, the TFT panel includes a plurality of first gate linesformed in the low-resolution area, a plurality of second gate linesformed in the high-resolution area, a plurality of first data linesintersected with the first gate lines and the second gate lines, theplurality of first data lines being insulated from the first and secondgate lines, and a plurality of second data lines intersected with andinsulated from the second gate lines, and not intersected with the firstgate lines.

The first data lines and the second data lines may be alternatelyarranged one by one, and an interval between two adjacent first gatelines may be about two times larger than an interval between twoadjacent second gate lines.

The LCD may further include a transflective LCD panel assembly and abacklight assembly for supplying light to the LCD panel assembly.

The transflective LCD panel assembly may include a TFT panel thatincludes a reflective electrode formed on a transparent electrode andhaving a transmissive window, a color filter panel that is opposed tothe TFT panel with a predetermined interval therebetween, a liquidcrystal layer interposed between the TFT panel and the color filterpanel, and a first polarizer and a second polarizer that arerespectively provided on outer surfaces of the TFT panel and the colorfilter panel.

The TFT panel may include a plurality of first gate lines formed in thelow-resolution area, a plurality of second gate lines formed in thehigh-resolution area, a plurality of first data lines that areintersected with and insulated from the first gate lines and the secondgate lines, and a plurality of second data lines that are intersectedwith and insulated from the second gate lines, and not intersected withthe first gate lines.

According to another embodiment of the present invention, there isprovided a liquid crystal display (LCD) device comprising alow-resolution area and a high-resolution area, wherein a pixel formedin the low-resolution area is larger than a pixel formed in thehigh-resolution area, and at least a part of the low-resolution areaexhibits only one color.

Preferably, a pixel formed in the low-resolution area is about threetimes as large as a pixel formed in the high-resolution area.

Preferably, a matrix of pixels formed in the low-resolution areacorresponds to a matrix of pixel groups formed in the high-resolutionarea, each pixel group consisting of R, G, and B pixels represented as adot in the high-resolution area.

Preferably, the data lines for supplying image signals to green pixelsof the high-resolution area extend up to the low-resolution area so thatall pixels formed in the low-resolution area may receive the imagesignals.

The low-resolution area may exhibit white and black, and a plurality ofmonochrome areas, each exhibiting only one color, may be included in thelow-resolution area. Each monochrome area may exhibit a different colorfrom the other areas. Further, at least one among the monochrome areasmay be comprised of pixels, each having two kinds of color filters.

According to another embodiment of the present invention, there isprovided a liquid crystal display (LCD) device comprising alow-resolution area and a high-resolution area, wherein thelow-resolution area includes a plurality of first gate lines and aplurality of first data lines, and the high-resolution area includes aplurality of second gate lines and a plurality of second data lines,wherein a pixel formed in the low-resolution area is larger than a pixelformed in the high-resolution area, and wherein each of the first datalines extends in a length direction of the low-resolution area.

Preferably, the second data lines extend to be perpendicular to thefirst data lines.

This LCD device may further include a first gate driving circuitprovided at a lateral side of the low-resolution area and extending inthe length direction of the low-resolution area, the first gate drivingcircuit supplying scanning signals to the first gate lines.

The LCD device may further include a second gate driving circuitprovided at a lateral side of the high-resolution area and extending inthe same direction as the second data lines, the second gate drivingcircuit supplying scanning signals to the second gate lines.

Further, the LCD device may include a data driving circuit for supplyingimage signals to the first data lines and the second data lines and awire for connecting the data driving circuit to the first data lines.

According to another embodiment of the present invention, there isprovided a liquid crystal display (LCD) device comprising a display partthat is divided into a plurality of display regions, a plurality oflight source parts each including a light source for supplying light toa corresponding display region, and a light source controller forcontrolling a supply of voltage to the light source parts to controloperation of the light source parts in response to control signalsapplied from an exterior device.

Preferably, the display part is divided into the plurality of displayregions on the basis of resolution.

The display part may include a main display part of higher resolutionand a sub display part of lower resolution.

The plurality of the light source parts may include a main light sourcepart for supplying light to the main display part and a sub light sourcepart for supplying light to the sub display part. Preferably, the mainlight source part includes more light sources than the sub light sourcepart.

The light sources of the main light source part may be arranged inseries or in parallel. Further, the light sources of the main lightsource part and the sub light source part may be light emitting diodes.

The LCD device may further include a plurality of power supply parts foroutputting a voltage necessary for the operation of the respective lightsource parts, wherein the light source controller outputs a controlsignal capable of driving the plurality of power supply parts.

The plurality of light source parts may be individually provided at atop and a bottom of the display part.

Alternatively, the plurality of light source parts may be individuallyprovided to the left or right of the display part.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention can be understood in moredetail from the following descriptions taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is an exploded perspective view schematically illustrating an LCDaccording to an embodiment of the present invention.

FIG. 2A is a layout view of an LCD according to an embodiment of thepresent invention.

FIG. 2B is a view showing pixels arranged in the LCD of FIG. 2A.

FIG. 3 shows two views for comparing a pixel unit formed in alow-resolution area with a pixel unit formed in a high-resolution areaof the LCD shown in FIG. 2B.

FIG. 4 is a layout view of a pixel unit in an LC panel of an LCDaccording to an embodiment of the present invention.

FIG. 5 is a cross-sectional view cut along the line V-V′ of FIG. 4.

FIG. 6 is a layout view of a driving circuit of an LCD according to anembodiment of the present invention.

FIG. 7 is a layout view of a driving circuit of an LCD according toanother embodiment of the present invention.

FIG. 8 is a layout view of a pixel unit formed in an LC panel of an LCDaccording to another embodiment of the present invention.

FIG. 9 is a cross-sectional view cut along the line IX-IX′ of FIG. 8.

FIG. 10A is a layout view of an LC panel according to another embodimentof the present invention.

FIG. 10B is a view enlarging a portion A of FIG. 10A.

FIG. 11A is a layout view of an LC panel according to another embodimentof the present invention.

FIG. 11B is a view enlarging a portion A of FIG. 11A.

FIG. 12A is a layout view of an LC panel according to another embodimentof the present invention.

FIG. 12B is a view enlarging a portion A of FIG. 12A.

FIG. 13 is a layout view of a driving circuit of an LCD according toanother embodiment of the present invention.

FIG. 14 is a block diagram of an LCD according to another embodiment ofthe present invention.

FIG. 15 is an equivalent circuit view of a pixel unit of an LCDaccording to another embodiment of the present invention.

FIG. 16 is a block diagram of a power supply part according to anembodiment of the present invention.

FIG. 17A and FIG. 17B are views for comparing arrangements of two mainlight sources respectively provided in two LCDs according to anembodiment of the present invention.

FIG. 18 is an exploded perspective view schematically illustrating anLCD according to another embodiment of the present invention.

FIG. 19A and FIG. 19B are views for comparing arrangements of two mainlight sources respectively provided in two LCDs according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described morefully hereinafter with reference to the accompanying drawings. Thepresent invention may, however, be embodied in different forms andshould not be construed as being limited to the embodiments set forthherein.

FIG. 1 is an exploded perspective view schematically illustrating an LCDaccording to an embodiment of the present invention.

Referring to FIG. 1, an LCD according to an embodiment of the presentinvention includes an LC panel assembly 330 for displaying images usinglight, a backlight assembly 340 for producing light, a selectivereflection film 347 provided between the LC panel assembly 330 and thebacklight assembly 340, a mold frame 364 for receiving the LC panelassembly 330, the selective reflection film 347, and the backlightassembly 340 therein, and an upper chassis 361 and a lower chassis 362that surround and support the above-mentioned elements.

The LC panel assembly 330 includes an LC panel 300 for exhibitingimages, a driving chip 510, and a malleable circuit board 550.

The LC panel 300 includes a thin film transistor (TFT) panel 100 and acolor filter panel 200 facing each other, and an LC layer (not shown)interposed therebetween.

The TFT panel is provided with a plurality of pixels (not shown)arranged substantially in a matrix. The pixels are defined byintersecting a plurality of gate lines (not shown) extending in a rowdirection while being parallel to each other, with a plurality of datalines (not shown) extending in a column direction while being parallelto each other. Each pixel is provided with a pixel electrode and a TFT(not shown) connected to a gate line, a data line, and a pixelelectrode.

The color filter panel 200 is provided with a plurality of red, green,and blue (RGB) filters (not shown) capable of displaying desired colorsusing white light and produced by thin film processes. The color filterpanel 200 also includes a common electrode opposite to the pixelelectrodes of the TFT panel 100.

The voltages applied to the pixel electrodes and the common electrodealign LC molecules in the LC layer, and the polarization of the lightsupplied from the backlight assembly 340 is varied according to theorientations of the LC molecules.

The driving chip 510 is mounted on a first edge of the TFT panel 100 tosupply driving signals to the data lines and the gate lines. The drivingchip 510 may include more than one chip, separately used for the gatelines and the data lines, or only one chip supplying the driving signalsto both the data and gate lines. When the driving chip 510 is mounted onthe TFT panel 100, a chip on glass (COG) technique is used.

The malleable circuit board 550 is attached to a first end of the TFTpanel 100 in order to apply control signals to the driving chip 510. Themalleable circuit board 550 includes a timing controller for controllingtiming of the driving signals or a memory for storing the data signals.The malleable circuit board 550 is electrically connected to the TFTpanel 100, with an anisotropy conductive film interposed therebetween.

The backlight assembly 340 is provided under the LC panel assembly 330to supply a uniform light thereto.

The backlight assembly 340 includes a light source 344 for producinglight, a light guiding plate 342 for guiding a proceeding path of light,optical sheets 343 for dispersing the incident light from the lightguiding plate 342 uniformly, and a reflection plate 341 for reflectinglight leaked from the light guiding plate 342.

The light source 344 is placed on a side of the light guiding plate 342to emit light toward the light guiding plate 342. Such a light source344 may utilize a linear light source, such as, for example, cathodefluorescent lamps (CCFLs) and external electrode fluorescent lamps(EEFLs), as well as light emitting diodes (LEDs), of which powerconsumption is relatively low. Another malleable circuit board (notshown) is attached to a side of the light source 344 to control it. Inthis embodiment, the light source 344 is provided on only one side ofthe light guiding plate 342 as mentioned above. Alternatively, the lightsource 344 may be provided on both sides of the light guiding plate 342.In addition, a plurality of light sources may be provided under thelight guiding plate 342. In such a case, the light guiding plate 342 maybe omitted.

The light guiding plate 342 has a light guiding pattern (not shown)capable of directing the light toward a display region of the LC panel300.

The optical sheets 343 are provided between the light guiding plate 342and the LC panel 300. The optical sheets 343 disperse the incident lightfrom the light guiding plate 342 uniformly and then supply the uniformlydispersed light to the LC panel 300.

Meanwhile, the selective reflection film 347 is provided between the LCpanel assembly 330 and the backlight assembly 340. This reflection film347 reflects the ambient light toward the LC panel 300 when the lightsource 344 is turned off, in order for the images to be displayed on thedisplay region in the case when the light source 344 is off. This ispossible because the reflection film 347 is designed to transmit andreflect light, selectively. That is, when the light source 344 is turnedon, the reflection film 347 transmits the incident light from thebacklight assembly 340 and supplies it to the LC panel 300. Conversely,when the light source 344 is turned off, the reflection film 347reflects the ambient light entering through the LC panel 300, toward theLC panel 300, in order for the images to be displayed on the displayregion.

The reflection plate 341 is provided under the light guiding plate 342.The light leaked from the light guiding plate 342 is reflected by thisreflection plate 341 and returned toward the light guiding plate 342,thereby improving light efficiency.

The mold frame 364 receives, in order, the reflection plate 341, thelight guiding plate 342, the optical sheets 343, and the LC panel 300.The mold frame 364, including resin plastics, is provided with an openbottom 251 and sidewalls 252 extending from the bottom 251.

The malleable circuit board 550 is curved along an outer portion of thesidewalls 252 of the mold frame 364. A plurality of first protrusions 51are formed on the outer portion of the sidewalls 252 of the mold frame364, which are combined with the lower chassis 362.

The lower chassis 362, including a metallic material, defines a spacefor accommodating the mold frame 364 therein. The lower chassis 362includes a bottom 261 and sidewalls 262 extending upward from the bottom261. A plurality of grooves 61 are formed on the sidewalls 262 of thelower chassis 362, which are combined with the protrusions 51 of themold frame 364.

When the mold frame 364 is combined with the lower chassis 362, part ofthe sidewalls 262 of the lower chassis 362 are placed on the outerportion of the sidewalls 252 of the mold frame 364, and each of thefirst protrusions 51 is inserted through the respective grooves 61 ofthe lower chassis 362. At this time, it is preferable to form portionsof the mold frame 364 that contact the sidewalls 262 of the lowerchassis 362, such that the mold frame is depressed by an amount equal toabout a thickness of the sidewalls 262.

The upper chassis 361 is provided above the LC panel 300. When the upperchassis 361 is assembled with the lower chassis 362, an effectivedisplay region of the LC panel 300 where the image display is realizedis kept in an open state. The upper chassis 361 guides a position of theLC panel 300 and then fixes the LC panel in the mold frame 364.

The LC panel 300 according to an embodiment of the present inventionwill be described with reference to FIGS. 2A and 2B, and FIG. 3.

FIG. 2A is a layout view of an LCD according to an embodiment of thepresent invention and FIG. 2B is a view showing pixels arranged in theLCD of FIG. 2A. FIG. 3 shows two views for comparing a pixel unit formedin a low-resolution area with a pixel unit formed in a high-resolutionarea of the LCD shown in FIG. 2B.

Referring to FIG. 2A and FIG. 2B, a driving chip 510 is mounted under anLC panel 300, and a display region of the LC panel 300 is divided into alow-resolution area and a high-resolution area.

Each pixel formed in the low-resolution area is four times as large as apixel formed in the high-resolution area. The low-resolution area isused as an auxiliary display part for displaying fixed patterns, such astime, antenna sensitivity, the remaining battery capacity or the like,in, for example, mobile technologies.

The high-resolution area is used as a main display part for displayingvarious and detailed images.

Referring to FIG. 3, the pixel unit of the low-resolution area is fourtimes as large as the pixel unit of the high resolution area, but thesize of wires, such as gate lines 121 and data lines 171, and TFTs arethe same in the two areas. Accordingly, an aperture ratio of thelow-resolution area is higher than that of the high-resolution area. Forexample, a 1.8-inch LCD panel having a resolution of 128×160 exhibits anaperture ratio of about 53%. When, like the low resolution area, thepixel size increases four times as large as that of the 1.8-inch LCDpanel having the resolution of 128×160, the aperture ratio increases toabout 76%. That is, the aperture ratio in the lower-resolution area isincreased by about 43% compared to that in the higher-resolution area.

Although the light reflected by the selective reflection film 347 isexclusively used for the image display when the light source 344 of FIG.1 is turned off, good quality image display can be realized due to theincreased aperture ratio.

If a selective reflection film 347 was used in conventional LCDs, itwould be difficult to represent the desired images accurately when thelight source 344 was turned off, since light efficiency in that case istoo low. Whereas, when each pixel formed in an image display area has alarge dimension, as in an embodiment of the present invention, goodquality image display becomes possible using only the selectivereflection film 347 when the light source 344 is turned off in order toreduce the power consumption.

For example, in LCDs employed in mobile units, the backlights are turnedon only when the mobile units are used to reduce power consumption.However, information about time or remaining power, for example, shouldbe continuously displayed in order to confirm them at any time. For thisreason, a proposed technique is to divide the display region of the LCpanel into a low-resolution area and a high-resolution area. In thiscase, the low-resolution area displays information that should bedisplayed all the time, while the high-resolution area displays otherinformation connected with the actual use of the mobile unit. Such anLCD allows some primary information to be displayed even when the lightsource is turned off in order to save power.

In this embodiment, each pixel formed in the low-resolution area isconfigured to have a dimension corresponding to a 2×2 matrix, namely,four times the size of a pixel formed in the high resolution area, butsuch a dimension may be altered as necessary.

Hereinafter, the structure of the LC panel 300 (shown in FIG. 1) will bedescribed in more detail. The pixels of the high-resolution area and thelow-resolution area have the same structure, except for theirdimensions.

FIG. 4 is a layout view of a pixel unit in an LC panel of an LCDaccording to an embodiment of the present invention and FIG. 5 is across-sectional view cut along V-V′ of FIG. 4.

The TFT panel 100 is configured as below.

A plurality of gate lines 121 are formed on an insulating substrate 110and transmit gate signals. Each gate line 121 extends substantially in ahorizontal direction, and includes a plurality of gate electrodes 124,and an end portion 125 having a relatively large dimension to beconnected to an external device. The gate lines 121 are disposed on thedisplay region except for the end portions 125 thereof, which arepositioned around the display region. In the case that a gate drivingcircuit is directly integrated into the TFT panel 100, the enlarged endportions 125 may be omitted.

The gate lines 121 include two layers having different physicalproperties, i.e., an upper layer 121 q and a lower layer 121 p. Theupper layer 121 q comprises a low resistivity metal, for example, analuminum (Al) containing metal, such as Al and Al alloy, in order toreduce delay of gate signals and voltage drop. The lower layer 121 pcomprises a material having prominent physical, chemical, and electricalcontact properties with other materials, particularly indium tin oxide(ITO) and indium zinc oxide (IZO). For example, Mo, Mo alloy (forexample, MoW), Cr, Ta, or Ti, may be used for the formation of the lowerlayer 121 p. A preferred example of the combination of the two layers isa lower Cr layer and an upper AINd layer. In FIG. 5, a lower layer andan upper layer of the gate electrode 124 are individually represented as124 p and 124 q. Further, each end portion 125 of the gate lines 121includes two layers, a lower layer 125 p and an upper layer 125 q.

The sides of the lower layer 121 p and the upper layer 121 q slope byabout 30° to about 80° with respect to the surface of the substrate 110.

A gate insulating layer 140 comprising, for example, nitride silicon(SiNx), is formed on the gate lines 121.

A plurality of semiconductors 150 comprising, for example, hydrogenatedamorphous silicon, abbreviated as “a-Si”, are formed on the gateinsulating layer 140. Each semiconductor 150 is formed substantially onthe gate electrode 124, covering a wide region including the gateelectrode 124.

A plurality of island-shaped ohmic contacts 163 and 165 are individuallyformed on the semiconductors 150, and comprise, for example, silicide orN+ hydrogenated amorphous silicon, highly doped with N-type impurities.A set of the island-shaped ohmic contacts 163 and 165 are placed on thesemiconductors 150.

The sides of the semiconductors 150 and the ohmic contacts 163 and 165slope by about 30° to about 80° with respect to the surface of thesubstrate 110.

A plurality of data lines 171 and a plurality of drain electrodes 175are formed on the ohmic contacts 163 and 165 and the gate insulatinglayer 140.

The data lines 171 extend substantially in a vertical direction to becrossed with the gate lines 121 and transmit data voltage. Each dataline 171 includes an end portion 179 having a relatively large dimensionto be connected to an external device. The data lines 171 are disposedon the display region except for the end portions 179 thereof, which arepositioned around the display region.

Each data line 171 includes a plurality of source electrodes 173protruding therefrom and corresponding to respective drain electrodes175, and each having the shape of a branch. A set of the drainelectrodes 175 and the source electrodes 173 are separated from eachother and face each other. The gate electrode 124, the source electrode173, the drain electrode 175, and the semiconductor 150 form a TFT, anda TFT channel is formed at the semiconductor 150 provided between thesource electrode 173 and the drain electrode 175.

Each data line 171 and each drain electrode 175 also have thedouble-layered structure. Lower layers 171 p and 175 p comprise, forexample, Mo, Cr, Ta, Ti or alloys thereof, and upper layers 171 q and175 q comprise, for example, a metallic material such as an Alcontaining metal or an Ag containing metal. Each end portion 179 of thedata lines 171 has an upper layer 179 q and a lower layer 179 p.

Similar to the gate lines 121, the sides of the lower layers 171 p and175 p and the upper layers 171 q and 175 q of the data lines 171 and thedrain electrodes 175 also slope by about 30° to about 80° with respectto the surface of the substrate 110.

The ohmic contacts 163 and 165 are interposed between the underlyingsemiconductors 150 and the overlying data lines 171 and between theunderlying semiconductors 150 and the overlying drain electrodes 175, inorder to reduce contact resistance therebetween.

A passivation layer 180 is formed on the data lines 171, the drainelectrodes 175, and the exposed areas of the semiconductors 151. Thepassivation layer 180 preferably comprises a photosensitive organicmaterial having prominent planarization properties, an insulatingmaterial having a relatively low dielectric constant of below 4.0, suchas, for example, a-Si:C:O or a-Si:O:F, which are produced by plasmaenhanced chemical vapor deposition (PECVD), or an inorganic materialsuch as, for example, SiN₂.

The passivation layer 180 has a plurality of contact holes 185 and 189,through which the end portions 179 of the data lines 171 and drainelectrodes 175 are exposed, respectively. A plurality of contact holes182 are formed to penetrate the passivation layer 180 and the gateinsulating layer 140, through which the enlarged end portions 125 of thegate lines 121 are exposed.

A plurality of pixel electrodes 190 and a plurality of contactassistants 906 and 908, comprising a transparent conductive materialsuch as, for example, ITO or IZO, are formed on the passivation layer180.

The pixel electrodes 190 are physically and electrically connected tothe drain electrodes 175 through the contact holes 185 to receive datavoltages from the drain electrodes 175.

The pixel electrodes 190 are overlapped with the adjacent gate line 121and the adjacent data line 171 to increase the aperture ratio, but theyare not overlapped with each other.

The contact assistants 906 and 908 are individually connected to the endportions 125 of the gate lines 121 and the end portions 179 of the datalines 171 through the contact holes 182 and 189. The contact assistants906 and 908 supplement adhesion between the enlarged end portions 125and 179 and the exterior devices, and protect the end portions 125 and179. The contact assistants may be omitted in some cases.

The color filter panel 200 is configured as below, as shown in FIG. 5.

A black matrix 220 is formed on an insulating substrate 210, and aplurality of color filters 230 are formed thereon. The respective colorfilters 230 are provided at each pixel unit and are defined by the blackmatrix 220. Red, green, and blue (RGB) color filters are used. A regionhaving no color filter may be formed on the color filter panel 200 orwhite color filters made of transparent resin may be additionally used.

A common electrode 270 comprising a transparent conductive material suchas, for example, ITO or IZO, is formed on the color filters 230.

A liquid crystal layer 3 is interposed between the TFT panel 100 and thecolor filter panel 200, and includes twisted nematic liquid crystalmolecules.

This embodiment uses the twisted aligned liquid crystal molecules.However, it is also possible to use the liquid crystal molecules alignedvertically or parallel with respect to the two panels 100 and 200, whilebeing parallel to each other.

A lower polarizer 12 and an upper polarizer 22 are respectively providedon the outer surfaces of the two panels 100 and 200.

In the LCD according to the present embodiment, when a common voltage isapplied to the common electrode 270 of the color filter panel 200 whilean image signal voltage is applied to the pixel electrode 190 throughthe data line 171, an electric field is generated between the twoelectrodes, so that the orientations of the liquid crystal moleculesinterposed between the two electrodes are varied.

Also, a set of the pixel electrode 190 and the common electrode 270serves as a capacitor capable of storing the applied voltage even afterthe TFT is turned off. This capacitor is referred to as a “liquidcrystal capacitor”. To enhance the voltage storage ability, a “storagecapacitor” may be further provided, which is connected to the liquidcrystal capacitor in parallel. To form such a storage capacitor, storageelectrode lines (not shown) may be formed on the same layer as the gatelines 121.

In the embodiments according to the present invention, the displayregion in the LC panel 300 is divided into a high-resolution area and alow-resolution area as mentioned above. A method for driving the twoareas will be described below.

FIG. 6 is a layout view of a driving circuit of an LCD according to anembodiment of the present invention and FIG. 7 is a layout view of adriving circuit of an LCD according to another embodiment of the presentinvention.

First, referring to FIG. 6, a driving chip 510 is mounted on an LC panel300, a gate driver 411 for driving the low-resolution area is providedat the left of the low-resolution area, and a gate driver 412 fordriving the high-resolution area is provided at the right of thehigh-resolution area. Here, the gate drivers 411 and 412 may be mountedon the corresponding areas of a TFT panel 100 in the shape of chips, ormay be directly integrated into the corresponding areas.

The TFT panel 100 includes gate lines 121 a of the low-resolution areaand 121 b of the high-resolution area. Data lines 171 a (e.g., evenlines) are insulated from, and intersected with, all of the gate lines121 a and 121 b, while data lines 171 b (e.g., odd lines) are insulatedfrom, and intersected with, only the gate lines 121 b of thehigh-resolution area. In this structure, an interval between twoadjacent gate lines 121 a formed in the low-resolution area is twice aslarge as an interval between two adjacent gate lines 121 b formed in thehigh-resolution area.

In such a configured LCD according to an embodiment of the presentinvention, in order to display images only at the low-resolution area,driving signals may be applied only to the gate driver 411 of thelow-resolution area, and not to the gate driver 412 of thehigh-resolution area. As a result, the data lines 171 supply necessaryimage signals only to the data lines 171 a that traverse the tworesolution areas.

Next, referring to FIG. 7, a gate driver 410 is provided at the left ofthe low-resolution area and the high-resolution area, traversing the twoareas. Here, the gate driver 410 may be mounted on a TFT panel 100 inthe shape of a chip, or may be directly integrated into the TFT panel100.

In such a configured LCD according to an embodiment of the presentinvention, when the high-resolution area receives only gate-off signalscontinuously while the low-resolution area receives gate-on and -offsignals, image display is realized only at the low-resolution area. Inthis case, the data lines 171 supply necessary image signals only to thedata lines 171 a that traverse the two resolution areas.

According to the above-described embodiments, no driving signal or onlythe gate-off signals are applied to the high-resolution area, in orderto display the images only at the low resolution area. However, it isalso possible to apply the gate-on and -off signals to thehigh-resolution area.

The embodiments of the present invention are applicable to transflectivetype LCDs.

A transflective LCD applying the embodiments of the present inventionhas the same structure as FIG. 1, except that the selective reflectionfilm 347 is eliminated.

Similar to FIG. 2A through FIG. 3, an LCD panel 300 of the transflectiveLCD is also divided into a low-resolution area and a high-resolutionarea, and each pixel unit of the low-resolution area is larger than thatof the high-resolution area.

The transflective LCD applying the embodiments of the present inventionwill be described with reference to FIG. 8 and FIG. 9.

FIG. 8 is a layout view of a pixel unit formed in an LC panel of an LCDaccording to another embodiment of the present invention and FIG. 9 is across-sectional view cut along IX-IX′ of FIG. 8.

A TFT panel 100 according to the present embodiment is configured asbelow.

A plurality of gate lines 121 are formed on an insulating substrate 110and transmit gate signals. Each gate line 121 extends substantially in ahorizontal direction, and includes a plurality of gate electrodes 124,and an end portion 125 having a relatively large dimension to beconnected to an external device. The gate lines 121 are disposed on thedisplay region except for the end portions 125 thereof, which arepositioned around the display region. In the case that a gate drivingcircuit is directly integrated into the TFT panel 100, the enlarged endportions 125 may be omitted.

The gate lines 121 include two layers having different physicalproperties, i.e., an upper layer 121 q and a lower layer 121 p. Theupper layer 121 q comprises a low resistivity metal, for example, analuminum (Al) containing metal, such as Al and Al alloy, in order toreduce a delay of the gate signals and a voltage drop. The lower layer121 p comprises a material having prominent physical, chemical, andelectrical contact properties with other materials, particularly indiumtin oxide (ITO) and indium zinc oxide (IZO). For example, Mo, Mo alloy(for example: MoW), Cr, Ta, or Ti, may be used for the formation of thelower layer 121 p. A preferred example of the combination of the twolayers is a lower Cr layer and an upper AINd layer. In FIG. 9, a lowerlayer and an upper layer of the gate electrode 124 are individuallyrepresented as 124 p and 124 q. Further, each end portion 125 of thegate lines 121 includes two layers, a lower layer 125 p and an upperlayer 125 q.

The sides of the lower layer 121 p and the upper layer 121 q slope byabout 30° to about 80° with respect to the surface of the substrate 110.

A gate insulating layer 140 comprising, for example, nitride silicon(SiNx), is formed on the gate lines 121.

A plurality of semiconductors 150 comprising, for example, hydrogenateda-Si, are formed on the gate insulating layer 140. Each semiconductor150 is formed substantially on the gate electrode 124, covering a wideregion including the gate electrode 124.

A plurality of island-shaped ohmic contacts 163 and 165 are individuallyformed on the semiconductors 150, and comprise, for example, silicide orN+ hydrogenated a-Si, highly doped with N-type impurities. A set of theisland-shaped ohmic contact 163 and 165 are placed on the semiconductor150.

The sides of the semiconductors 150 and the ohmic contacts 163 and 165slope by about 30° to about 80° with respect to the surface of thesubstrate 110.

A plurality of data lines 171 and a plurality of drain electrodes 175are formed on the ohmic contacts 163 and 165 and the gate insulatinglayer 140.

The data lines 171 extend substantially in a vertical direction to becrossed with the gate lines 121 and transmit data voltage. Each dataline 171 includes an end portion 179 having a relatively large dimensionto be connected to an external device. The data lines 171 are disposedon the display region except for the end portions 179 thereof, which arepositioned around the display region.

Each data line 171 includes a plurality of source electrodes 173protruding therefrom and corresponding to respective drain electrodes175, each having the shape of a branch. A set of the drain electrodes175 and the source electrodes 173 are separated from each other and faceeach other. The gate electrode 124, the source electrode 173, the drainelectrode 175, and the semiconductor 150 form a TFT, and a TFT channelis formed at the semiconductor 150 provided between the source electrode173 and the drain electrode 175.

Each data line 171 and each drain electrode 175 also have thedouble-layered structure. Lower layers 171 p and 175 p comprise, forexample, Mo, Cr, Ta, Ti or alloys thereof, and upper layers 171 q and175 q comprise, for example, a metallic material such as an Alcontaining metal or an Ag containing metal. Each end portion 179 of thedata lines 171 has an upper layer 179 q and a lower layer 179 p.

Similar to the gate lines 121, the sides of the lower layers 171 p and175 p and the upper layers 171 q and 175 q of the data lines 171 and thedrain electrodes 175 also slope by about 30° to about 80° with respectto the surface of the substrate 110.

The ohmic contacts 163 and 165 are interposed between the underlyingsemiconductors 150 and the overlying data lines 171 and between theunderlying semiconductors 150 and the overlying drain electrodes 175, inorder to reduce contact resistance therebetween.

A passivation layer 180 is formed on the data lines 171, the drainelectrodes 175, and the exposed areas of the semiconductors 151. Thepassivation layer 180 preferably comprises a photosensitive organicmaterial having prominent planarization properties, an insulatingmaterial having a relatively low dielectric constant of below about 4.0,such as, for example, a-Si:C:O or a-Si:O:F, which are produced by plasmaenhanced chemical vapor deposition (PECVD), or an inorganic materialsuch as, for example, SiN₂.

The passivation layer 180 has a plurality of contact holes 185 and 189,through which the end portions 179 of the data lines 171, and the drainelectrodes 175 are exposed, respectively. A plurality of contact holes182 are formed to penetrate the passivation layer 180 and the gateinsulating layer 140, through which the enlarged end portions 125 of thegate lines 121 are exposed.

A plurality of transparent electrodes 192 and a plurality of contactassistants 906 and 908, comprising a transparent conductive materialsuch as, for example, ITO or IZO, are formed on the passivation layer180.

A plurality of reflective electrodes 194 are individually formed on thetransparent electrodes 192, and comprise a conductive material havinggood reflection property, such as, for example, Ag. Each reflectiveelectrode 194 has a transmission window 195, where light is freelytransmitted.

A set of the transparent electrodes 192 and the reflective electrodes194 may serve as a pixel electrode 190, and each reflective electrode194 may serve as a reflective film for reflecting light.

The transparent electrodes 192 are physically and electrically connectedto the drain electrodes 175 through the contact holes 185 to receivedata voltages from the drain electrodes 175.

The contact assistants 906 and 908 are individually connected to the endportions 125 of the gate lines 121 and the end portions 179 of the datalines 171 through the contact holes 182 and 189. The contact assistants906 and 908 are supplement adhesion between the enlarged end portions125 and 179 and the exterior devices, and protect the end portions 125and 179. The contact assistants may be omitted.

The color filter panel 200 is configured as below, as shown in FIG. 9.

A black matrix 220 is formed on an insulating substrate 210, and aplurality of color filters 230 are formed thereon. The respective colorfilters 230 are provided at each pixel unit and defined by the blackmatrix 220. Red, green, and blue (RGB) color filters are used. A regionhaving no color filter may be formed on the color filter panel 200 orwhite color filters comprising transparent resin also may be used.

A common electrode 270 comprising a transparent conductive material suchas, for example, ITO or IZO, is formed on the color filters 230.

A liquid crystal layer 3 is interposed between the TFT panel 100 and thecolor filter panel 200, and includes twisted nematic liquid crystalmolecules.

This embodiment uses the twisted aligned liquid crystal molecules.However, it is also possible to use the liquid crystal molecules alignedvertically or parallel with respect to the two panels 100 and 200, whilebeing parallel to each other.

A lower polarizer 12 and an upper polarizer 22 are individually providedon the outer surfaces of the two panels 100 and 200, respectively.

The transflective LCD may be used in the reflective mode, reflectingambient light toward the LCD when the ambient light has a highbrightness suitable for the image display. However, in the case wherethe ambient light has insufficient brightness, the reflective mode isconverted to the transmissive mode, using the light emitted from thebacklight for the image display.

When the backlight is turned off to save power in such a transflectiveLCD, the low-resolution area is operated in the reflective mode, so thatnecessary information of a fixed pattern can be displayed at all times,regardless of the operation of the backlight.

The driving circuit or the driving chip of the transflective LCD havingthe two different resolution areas may be arranged as shown FIG. 6 andFIG. 7, and a driving method thereof is equivalent to the previouslyillustrated method.

FIG. 10A is a layout view of an LC panel according to another embodimentof the present invention and FIG. 10B is a view enlarging a portion A ofFIG. 10A.

Referring to FIG. 10A and FIG. 10B, an LCD of this embodiment includes ahigh-resolution area and a low-resolution area. In the high-resolutionarea, R, G, and B color filters are alternately provided at each pixelfor color display. In the low-resolution area, color filters are notprovided or W (white) color filters, comprising, for example, atransparent photoresist film or the like, are provided at each pixel toexhibit black and white. Here, a pixel formed in the low-resolution areais three times as large as a pixel formed in the high-resolution area.

As explained above, when the area of a pixel formed in thelow-resolution area is larger than the area of a pixel formed in thehigh-resolution area, for example, the area of a pixel in thelow-resolution area is equal to the sum area of three pixels formed inthe high-resolution area, and color filters are not provided or whitecolor filters only are provided in the low-resolution area, lightefficiency of the low-resolution area increases since the aperture ratioof the pixels increases and light absorption caused by the RGB colorfilters is not generated. Without the RGB color filters, the lighttransmittance increases almost three times and the aperture ratio alsoincreases. Accordingly, according to the present embodiment, thelow-resolution area obtains light efficiency approximately four timeshigher than that of the high-resolution area.

A set of R, G, and B pixels formed in the high-resolution area, eachbeing represented as a dot, corresponds to a pixel formed in thelow-resolution area, and therefore a matrix of such sets formed in thehigh-resolution area corresponds to a matrix of pixels formed in thelow-resolution area. Accordingly, all pixels formed in thelow-resolution area can receive image signals from the data lines, whichtraverse the two areas and supply image signals to the green pixels Gformed in the high-resolution area.

In this structure, according to an embodiment of the present invention,when the data lines connected to the green pixels G of thehigh-resolution area are connected to the pixels of the low-resolutionarea, the low-resolution area can exhibit black and white without anyparticular variation of the driving method or any image processing.

Further, as shown in FIG. 6, when the gate driver 412 for driving thehigh-resolution area and the gate driver 411 for driving thelow-resolution area are respectively provided to drive the two areasseparately, and the data driving chip 510 is only operated in the stillmode in order for the image display to be realized only at thelow-resolution area, power saving is possible by a factor of about 90%.

FIG. 11A is a layout view of an LC panel according to another embodimentof the present invention and FIG. 11B is a view enlarging a portion A ofFIG. 11A.

Referring to FIG. 11A and FIG. 11B, an LCD of this embodiment is dividedinto a high-resolution and a low-resolution area. The low-resolutionarea is further divided into two areas, an area having red color filtersR and an area having blue filters B. In the high-resolution area, R, G,and B color filters are alternately provided at each pixel to realizecolor display. Here, a pixel formed in the low-resolution area is threetimes as large as a pixel formed in the high-resolution area.

In this structure, the R, G, and B color filters may be formed all overthe low-resolution area. Alternatively, after the low-resolution area isdivided into the areas as shown in FIG. 11B, different color filters maybe formed at each area.

The low-resolution area may exhibit different colors according to a kindof information, for example, in time information may be blue, antennainformation may be green, and the battery charging state may be red.

FIG. 12A is a layout view of an LC panel according to another embodimentof the present invention and FIG. 12B is a view enlarging a portion A ofFIG. 12A.

Referring to FIG. 12A and FIG. 12B, an LCD of this embodiment is dividedinto a high-resolution and a low-resolution area. The low-resolutionarea is divided into two areas. In one area, each pixel is provided witha red color filter R and a blue filter B, each occupying a half of thepixel. In the other area, each pixel is provided with a green colorfilter G and a blue filter B, each occupying a half of the pixel. In thehigh-resolution area, R, G, and B color filters are alternately providedat each pixel to realize the color display. Here, a pixel formed in thelow-resolution area is three times as large as a pixel formed in thehigh-resolution area.

A method for realizing color display in the low-resolution area is todisplay different colors in the respective areas after dividing thelow-resolution area into more than three areas. Another method is todisplay only one color all over the low-resolution area. Further, asshown in FIG. 11B, a monochrome area may be included in thelow-resolution area.

The above-mentioned methods enable, for example, the displayed images inthe low-resolution area to have colors different from the primary colors(i.e., red, green and blue). For example, when the color filters aredisposed as shown in FIG. 12B, a left portion of the low-resolution areaexhibits violet V, while a right portion exhibits sky blue S.

FIG. 13 is a layout view of a driving circuit of an LCD according toanother embodiment of the present invention.

Referring to FIG. 13, data lines 171 a of a low-resolution area and datalines 171 b of a high-resolution area are formed in different ways. Indetail, the data lines 171 b of the high-resolution area extend in avertical direction and the data lines 171 a of the low-resolution areaextend in a horizontal direction to be perpendicular to the data lines171 b. Accordingly, an access-from part 792 of the data line 171 b isprovided at a lowermost portion of the high-resolution area to beconnected to the data driver 510, while an access-from part 791 of thedata line 171 a is provided at the right of the low-resolution area.

The access-from part 791 of the low-resolution area and the access-frompart 792 of the high-resolution area receive image signals from the datadriver 510 through wires 511 a and 511 b separately provided.

Gate lines 121 a of the low-resolution area extend in a verticaldirection to be perpendicular to the data lines 171 a, and gate lines121 b of the high-resolution area extend in a horizontal direction to beperpendicular to the data lines 171 b. Accordingly, a gate driver 411 ofthe low-resolution area is provided at a top of the low-resolution area,while a gate driver 412 of the high-resolution area is provided at theleft of the high-resolution area. Here, the gate drivers 411 and 412 maybe individually mounted on each corresponding area of a TFT panel 100,having the shape of chips, or may be directly integrated into eachcorresponding area.

The low-resolution area of this embodiment is shaped as a horizontallylong band, and the data lines 171 a are formed in a length direction ofthe low-resolution area, namely, in a horizontal direction. Accordingly,the number of the data lines 171 a allowable in this low-resolution areais less than that when they are formed in a width direction of thelow-resolution area, namely, in a vertical direction. For example, in anLCD having the resolution of 128×160, when the data lines 171 a of thelow-resolution area are formed in a width direction, an allowable numberof the data lines 171 a is 128×3 within such an area. Conversely, whenthe data lines 171 a are formed in a length direction of thelow-resolution area as in the present embodiment, an allowable number ofthe data lines 171 a is 32 (obtained by subtracting 128 from 160). Inthis case, however, the number of the gate lines 121 a increases.

When the number of the data lines 171 a of the low-resolution area isreduced as mentioned in the above, the number of the wires 511 a forconnecting the data driver 510 to the access-from part 791 of thelow-resolution area is also reduced. In view of design, such a reductionof the wires 511 a facilitates an arrangement of the wires.

Meanwhile, even if the number of the gate lines 121 a increases, thenumber of the wires 512 a for connecting the data driver 510 to the gatedriver 411 is nevertheless unchanged, since the gate driver 411, forsupplying scanning signals to the gate lines 121 a, is provided at thetop of the low-resolution area and a kind of signals applied to the gatedriver 411 through the data driver 510 is unchanged, regardless of thechange of the number of gate lines 121 a.

As mentioned in the above, in accordance with embodiments of the presentinvention, a low-resolution area and a high-resolution area are formedin the LCD panel and some information of fixed patterns that needdisplaying at all times, are displayed in the low resolution area of thetwo areas.

Accordingly, the present invention allows certain types of informationto be displayed at all times, while power consumption is reduced.

Some margin in a manufacturing process can be expected by adopting gatedrivers capable of separately driving the high-resolution area and thelow-resolution area, with efficiently designed wires.

An LCD according to another embodiment of the present invention will bedescribed in detail with reference to FIG. 1, FIG. 14, and FIG. 15.

FIG. 14 is a block diagram of an LCD according to another embodiment ofthe present invention and FIG. 15 is an equivalent circuit view of apixel unit of an LCD according to another embodiment of the presentinvention.

Referring to FIG. 1 again, an LCD includes an LC panel assembly 330 fordisplaying images using light, a backlight assembly 340 for producinglight, a selective reflection film 347 provided between the LC panelassembly 330 and the backlight assembly 340, a mold frame 364 forreceiving the LC panel assembly 330, the selective reflection film 347,and the backlight assembly 340 therein, and an upper chassis 361 and alower chassis 362 that surround and support the above-mentionedelements.

The LC panel assembly 330 includes an LC panel 300, a driving chip 510,and a malleable circuit board 550.

The LC panel 300 includes a lower panel 100 and an upper panel 200facing each other, and an LC layer (not shown) interposed therebetween.

Referring to FIG. 14, the lower panel 100 includes a plurality ofdisplay signal lines G₁-G_(n) and D₁-D_(m), The lower panel 100 and theupper panel 200 include a plurality of pixels connected to the displaysignal lines G₁-G_(n), and D₁-D_(m) and arranged substantially in amatrix.

The display signal lines G₁-G_(n) and D₁-D_(m) include a plurality ofgate lines G₁-G_(n) for transmitting gate signals (also referred to as“scanning signals”), and a plurality of data lines D₁-D_(m) fortransmitting data signals. The gate lines G₁-G_(n) extend substantiallyin a row direction and substantially parallel to each other, while thedata lines D₁-D_(m) extend substantially in a column direction andsubstantially parallel to each other.

Each pixel includes a switching element Q that is connected to thedisplay signal lines G₁-G_(n) and D₁-D_(m), and an LC capacitor C_(LC)and a storage capacitor C_(ST) that are connected to the switchingelement Q. The storage capacitor C_(ST) may be omitted.

The switching element Q, such as a thin film transistor (TFT), isprovided on the lower panel 100 and has three terminals: a controlterminal connected to one of the gate lines G₁-G_(n); an input terminalconnected to one of the data lines D₁-D_(m); and an output terminalconnected to both of the LC capacitor C_(LC) and the storage capacitorC_(ST).

As shown in FIG. 15, the LC capacitor C_(LC) includes a pixel electrode190, provided on the lower panel 100, and a common electrode 270,provided on the upper panel 200, as two terminals. The LC layer 3interposed between the two electrodes 190 and 270 functions as adielectric of the LC capacitor C_(LC). The pixel electrode 190 isconnected to the switching element Q, and the common electrode 270 issupplied with a common voltage V_(com), and covers the entire surface ofthe upper panel 200. Differing from FIG. 15, the common electrode 270may be provided on the lower panel 100. In this case, at least one ofthe pixel electrode 190 and the common electrode 270 may be shaped as abar or a stripe.

The storage capacitor C_(ST) is an auxiliary capacitor for the LCcapacitor C_(LC). When the pixel electrode 190 and a separate signalline (not shown), which is provided on the lower panel 100, areoverlapped with each other, with an insulator interposed therebetween,the overlapped portion becomes the storage capacitor C_(ST). Theseparate signal line is supplied with a predetermined voltage such asthe common voltage V_(com). Alternatively, the storage capacitor C_(ST)may be formed by overlapping of the pixel electrode 190 and a previousgate line that is placed directly before the pixel electrode 190, withan insulator interposed therebetween.

For color display, each pixel must exhibit a color. This is possiblewhen each pixel includes a color filter 230 capable of exhibiting one ofthe primary colors, red, green, and blue, in an area of the upper panel200 corresponding to the pixel electrode 190. In FIG. 14, the colorfilter 230 is provided on the upper panel 200, but it may be provided onor under the pixel electrode 190 of the lower panel 100.

A polarizer (not shown) is provided on at least one outer surface of thetwo panels 100 and 200 of the LC panel 300 for polarizing the lightemitted from the two-dimensional light source units.

The gate drivers 400 are individually connected to the gate linesG₁-G_(n) for transmitting the gate signals, consisting of combinationsof the gate-on voltage V_(on) and the gate-off voltage V_(off) inputfrom an external device, to the gate signal lines G₁-G_(n). The gatedrivers 400 are integrated into the lower panel 100 with the switchingelement Q and the display signal lines G₁-G_(n) and D₁-D_(m).

The driving chip 510 is directly mounted on the lower panel 100 of theLC panel 300, having the shape of an IC chip, as shown in FIG. 1, andincludes a signal controller 600, a data driver 500 connected to thesignal controller 600, and a gray voltage generator 800 connected to thedata driver 500.

The gray voltage generator 800 generates two sets of a plurality of grayvoltages related to the transmittance of the pixels. The gray voltagesin one set have positive polarity with respect to the common voltagev_(com), while those of the other set have negative polarity withrespect to the common voltage v_(com).

The data driver 500 is connected to the data lines D₁-D_(m) of the LCpanel 300 for transmitting the data voltages, which are selected fromthe gray voltages supplied from the gray voltage generator 800, to thedata signal lines D₁-D_(m).

The signal controller 600 controls the operation of the gate driver 400or the data driver 500.

The backlight assembly 340 is provided under the LC panel assembly 330for offering a uniform light to the LC panel 300.

The backlight assembly 340 includes a light source part 344 forproducing light, a light guiding plate 342 for guiding a proceeding pathof light, optical sheets 343 for uniformly dispersing the light inputfrom the light guiding plate 342, a reflection plate 341 for reflectinglight leaked from the light guiding plate 342, a light source controller348 connected to the signal controller 600, and a power supply part 349connected to the light source controller 348 and the light source part344.

The light source part 344 includes a main light source 3441 and a sublight source 3442, which are placed on two sides of the light guidingplate 342 to emit light toward the light guiding plate 342 (see FIG.18). The main light source 3441 and sub light source 3442 may freelyexchange their locations. This light source part 344 may utilize lightemitting diodes (LEDs), of which power consumption is relatively low, orfluorescent lamps such as, for example, cold cathode fluorescent lamps(CCFLs) or external electrode fluorescent lamps (EEFLs). The number ofthe LEDs may be controlled.

The light source controller 348 controls the operation of the powersupply part 349 in response to control signals from the signalcontroller 600.

The power supply part 349 supplies a driving voltage to the light sourcepart 344 according to the operation of the light source controller 348.

The light guiding plate 342 has a light guiding pattern (not shown)capable of directing light toward a display region of the LC panel 300.

The optical sheets 343 are provided between the light guiding plate 342and the LC panel 300. These optical sheets 343 disperse the incidentlight from the light guiding plate 342 uniformly and then supply it tothe LC panel 300.

The selective reflection film 347 is provided between the LC panelassembly 330 and the backlight assembly 340. This reflection film 347reflects the ambient light toward the LC panel 300 when the light source344 is turned off, in order for the images to be displayed on thedisplay region in such a case. This is possible because the reflectionfilm 347 is designed to transmit or reflect light, selectively. That is,when the light source 344 is turned on, the reflection film 347transmits the incident light from the backlight assembly 340 andsupplies it to the LC panel 300. Conversely, when the light source 344is turned off, the reflection film 347 reflects the ambient light,entering through the LC panel 300, toward the LC panel 300, in order forthe images to be displayed on the display region.

The reflection plate 341 is provided under the light guiding plate 342.The light leaked from the light guiding plate 342 is reflected by thisreflection plate 341 and returned toward the light guiding plate 342,thereby improving light efficiency.

The mold frame 364 receives, in order, the reflection plate 341, thelight guiding plate 342, the optical sheets 343, and the LC panel 300.The mold frame 364, comprising, for example, resin plastics, is providedwith an open bottom 251 and sidewalls 252 extending from the bottom 251.

The malleable circuit board 550 is curved along an outer portion of thesidewalls 252 of the mold frame 364. A plurality of first protrusions 51are formed on the outer portion of the sidewalls 252 of the mold frame364, which are combined with the lower chassis 362.

The lower chassis 362, comprising a metallic material, defines a spacefor accommodating the mold frame 364 therein, with a bottom 261 andsidewalls 262 extending upward from the bottom 261. A plurality ofgrooves 61 are formed on the sidewalls 262 of the lower chassis 362, andare combined with the protrusions 51 of the mold frame 364.

When the mold frame 364 is combined with the lower chassis 362, part ofthe sidewalls 262 of the lower chassis 362 are placed on the outersidewalls 252 of the mold frame 364, and each of the first protrusions51 is inserted through the respective grooves 61 of the lower chassis362. At this time, it is preferable to form portions of the mold frame364, that contact the sidewalls 262 of the lower chassis 362, such thatthe mold frame is depressed by an amount equal to about a thickness ofthe sidewalls 262.

The upper chassis 361 is provided above the LC panel 300. When the upperchassis 361 is assembled with the lower chassis 362, an effectivedisplay region of the LC panel 300 where the image display is realizedis kept in an open state. The upper chassis 361 guides a position of theLC panel 300 and then fixes it in the mold frame 364.

Hereinafter, the operation of the above-mentioned LCD will be described.

The signal controller 600 of the driving chip 510 receives input imagesignals R, G, and B and input control signals for controlling thedisplay thereof, such as, for example, a vertical synchronizing signalV_(sync), a horizontal synchronizing signal H_(sync), a main clock MCLK,and a data enable signal DE, from an external graphic controller (notshown).

In response to the input image signals R, G, and B and the input controlsignals, the signal controller 600 processes the image signals R, G, andB suitably for the operation of the LC panel 300 and generates gatecontrol signals CONT1 and data control signals CONT2, and then outputsthe gate control signals CONT1 and the data control signals CONT2 to thegate driver 400 and the data driver 500, respectively.

The gate control signals CONT1 include a vertical synchronizing startsignal STV for informing the output of the gate-on voltage V_(on), andat least one clock signal for controlling the output time and the outputvoltage of the gate-on voltage V_(on).

The data control signals CONT2 include a horizontal synchronizing startsignal STH for informing the beginning of data transmission, a loadsignal LOAD for instructing application of the data voltages to the datalines D₁-D_(m), a reverse signal RVS for reversing the polarity of thedata voltages with respect to the common voltage V_(com), and a dataclock signal HCLK.

Responsive to the data control signals CONT2 from the signal controller600, the data driver 500 successively receives the image data DAT for arow of the pixels from the signal controller 600, converts the imagedata DAT into analog data voltages selected from the gray voltages fromthe gray voltage generator 800, and then applies the data voltages todata lines D₁-D_(m) of the LC panel 300.

The gate driver 400 applies the gate-on voltage V_(on) to the gate linesG₁-G_(n) in response to the gate control signals CONT1 from the signalcontroller 600, thereby turning on the switching elements Q connectedthereto. The data voltages applied to the data lines D₁-D_(m) areapplied to the corresponding pixel through the activated switchingelements Q.

The difference between the data voltage applied to the pixel and thecommon voltage V_(com), is represented as a voltage across the LCcapacitor C_(Lc), namely, a pixel voltage. The LC molecules in the LCcapacitor C_(LC) have orientations depending on the magnitude of thepixel voltage.

The backlight assembly 340 controls switching of the light source (e.g.,LED) 344, based on a backlight control signal CONT3 that is applied froman exterior device according to the operation of the selected switchingelement Q or the operation of the LCD. Such an operation of thebacklight assembly 340 will be described next. The backlight controlsignal CONT3 may be applied from the signal controller 600.

When the light emitted from the LED 344 passes through the LC layer 3,the polarization of the light is varied according to the orientations ofthe LC molecules. The polarizer converts the difference of the lightpolarization into a difference of the light transmittance.

By repeating this procedure by a unit of the horizontal period (which isdenoted by “1H” and equal to one period of the horizontal synchronizingsignal H_(sync), the data enable signal DE, and the gate clock CPV), allgate lines G₁-G_(n) are sequentially supplied with the gate-on voltageV_(on) during a frame, thereby applying the data voltages to all pixels.When the next frame starts after finishing one frame, the reversecontrol signal RVS applied to the data driver 500 is controlled suchthat the polarity of the data voltages is reversed with respect to thatof the previous frame (which is referred to as “frame inversion”). Thereverse control signal RVS may also be controlled such that the polarityof the data voltages flowing along a data line in one frame is reversed(for example, line inversion and dot inversion), or the polarity of thedata voltages in one packet is reversed (for example, column inversionand dot inversion).

Hereinafter, the operation of the backlight assembly 340 will bedescribed with reference to FIG. 14, FIG. 16, FIG. 17A, and FIG. 17B.

FIG. 16 is a block diagram of a power supply part according to anembodiment of the present invention, and FIG. 17A and FIG. 17B are viewsfor comparing arrangements of two main light sources individuallyprovided in two LCDs according to embodiments of the present invention.

As illustrated in the above with reference to FIG. 14, the backlightassembly 340 includes the light source controller 348, the power supplypart 349 connected to the light source controller 348, the light sourcepart 344 that is connected to the power supply part 349 and includes themain light source 3441 and the sub light source 3442.

As shown in FIG. 16, the power supply part 349 includes a main powersupply part 981 and a sub power supply part 982.

The main power supply part 981 receives an input voltage V_(b) from aportable energy source (not shown) such as, for example, a battery, anda control signal EN1 from the light source controller 348, and thenoutputs a driving voltage V_(out1) and a ground voltage GND1 suitablefor the operation of the main light source 3441.

The sub power supply part 982 receives an input voltage V_(b) from aportable energy source (not shown) and a control signal EN2 from thelight source controller 348, and then outputs a driving voltage V_(out2)and a ground voltage GND2 suitable for the operation of the sub lightsource 3442.

The control signals EN1 and EN2 serve as enable signals of the main andsub light sources 3441 and 3442, applied from the light sourcecontroller 348, each determining whether to operate the main and subpower supply parts 981 and 982. That is, when the control signal EN1 orEN2 is in “high” level, the corresponding main and sub power supplyparts 981 or 982 operate, and when the control signal EN1 or EN2 is in“low” level, the corresponding main and sub power supply parts 981 or982 do not operate.

Referring to FIG. 17A, the main light source 3441 of the light sourcepart 344 includes a plurality of light sources, namely, four LEDs L1 toL4 connected to each other in series. A driving terminal A1 receives adriving voltage V_(out1) from the main power supply part 981, and aground terminal B1 receives a ground voltage GND1 from the main powersupply part 981.

The sub light source 3442 includes an LED L5. A driving terminal A2receives a driving voltage V_(out2) from the sub power supply part 982and a ground terminal B2 receives a ground voltage GND2 from the subpower supply part 982.

In the respective main and sub light sources 3441 and 3442, the numberof the LEDs may be altered.

The main light source 3441 is switched on or off, depending on theoperation of the main power supply part 981. That is, when the operationof the main power supply part 981 begins, the main power supply part 981supplies the driving voltage V_(out1) and the ground voltage GND1 to thecorresponding main light source 3441, so that the corresponding mainlight source 3441 is switched on. In a reverse case, the main lightsource 3441 is switched off.

Similarly, the sub light source 3442 is switched on or off, depending onthe operation of the sub power supply part 982. That is, when theoperation of the sub power supply part 982 begins, the sub power supplypart 982 supplies the driving voltage V_(out2) and the ground voltageGND2 to the corresponding sub light source 3442, so that thecorresponding sub light source 3442 is switched on. In a reverse case,the sub light source 3442 is switched off.

As shown in FIG. 17A, the display region of the LCD panel 300 accordingto an embodiment of the present invention is divided into a main displaypart 301 corresponding to the high-resolution area and a sub displaypart 302 corresponding to the low-resolution area. In this embodiment,the display region is divided into the two areas on the basis of theresolution, but various standards besides the resolution, for example,dimension of the display region, may also be used to divide the displayregion.

The main display part 301 is a region where various images can bedisplayed freely and minutely, while the sub display part 302 is aregion where fixed pattern images for informing, for example, time,antenna sensitivity, the remaining battery capacity, are displayed. Inspite of having lower resolution, the sub display part 302 has nodifficulty in displaying the fixed pattern images since such images canbe adequately represented with only minimum or maximum gray.

As shown in FIG. 17A, the main light source 3441 is provided at a lowerpart of the LC panel 300 adjacent to the main display part 301, in ahorizontal direction, and the sub light source 3442 is provided at anupper part of the LC panel 300 adjacent to the sub display part 302. Inthis case, the LEDs L1 to L4 of the main light source 3441 are arrangedto be close to the main display part 301, having regular intervalstherebetween, in order to supply uniformly dispersed light to the maindisplay part 301. Similarly, the LED L5 of the sub light source 3442 isarranged at a center of an upper portion of the LCD panel 300, wherelight emitted from the LED L5 can be most efficiently supplied to thesub display part 302 of the LCD panel 300. However, the arrangements ofsuch LEDs L1 to L5 may be changed.

The operation of the above-mentioned backlight assembly 340 will bedescribed below.

As mentioned above, the main and sub light sources 3441 and 3442 areindividually switched on or off, each depending on the operation of themain power supply part 981 and the sub power supply part 982.

That is, in response to a backlight control signal CONT3, the lightsource controller 348 checks the enable signals EN1 and EN2, eachrespectively applied to the main power supply part 981 and the sub powersupply part 982, and then outputs signals corresponding to the states ofthe enable signals EN1 and EN2. For example, when all of the maindisplay part 301 and the sub display part 302 are used, the light sourcecontroller 348 makes all of the states of the enable signals EN1 and EN2in high level. Alternatively, only the enable signal EN1 is in a highlevel when only the main display part 301 is used.

In addition, to display only primary information of a fixed pattern inthe sub display part 302, while the main display part 301 has no image,only the enable signal EN2 should be high. When the LCD does not operatefor longer than a predetermined time, all of the enable signals EN1 andEN2 are low. Alternatively, the main and sub light sources 3441 and3442, which are individually activated in response to the enable signalsEN1 and EN2, may operate differently from the above-mentioned manner.

When the main power supply part 981 operates according to the state ofthe corresponding enable signal EN1, the driving voltage V_(out1) isapplied to the driving terminal A1 of the corresponding main lightsource 3441, and the ground voltage GND1 is applied to the groundterminal B1, so that the main light source 3441 is turned on, emittinglight toward the corresponding main display part 301.

Also, when the sub power supply part 982 operates according to the stateof the corresponding enable signal EN2, the driving voltage V_(out2) isapplied to the driving terminal A2 of the corresponding sub light source3442, and the ground voltage GND2 is applied to the ground terminal B2,so that the sub light source 3442 is turned on, emitting light towardthe corresponding sub display part 302.

FIG. 17B shows another example of the main light source 3441 accordingto an embodiment of the present invention. The operation of this exampleis substantially to the same as that of the example previouslyillustrated with reference to FIG. 17A, except that the LEDs L1 to L4are arranged in parallel. In this structure, the main light source 3441consisting of the LEDs L1 to L4 is switched on or off, according towhether the driving signal V_(out1) and ground voltage GND1 suppliedfrom the main power supply part 981 are applied to the correspondingdriving terminal A1 and the corresponding ground terminal B1.

In this way, after the LCD panel 300 is divided into a plurality ofareas, the main and sub light sources 3441 and 3442 are individuallyswitched on or off according to the state of each divided area, so thatthe power consumption caused by unnecessary lighting of the main and sublight sources 3441 and 3442 may be reduced.

An LCD according to another embodiment of the present invention will bedescribed with reference to FIG. 18 through FIG. 19B.

FIG. 18 is an exploded perspective view schematically illustrating anLCD according to another embodiment of the present invention. FIG. 19Aand FIG. 19B are views for comparing arrangements of two main lightsources individually provided in two LCDs according to other embodimentsof the present invention.

The LCD of FIG. 18 is substantially the same as the LCD of FIG. 1,except for the positions of the main light source 3441 and the sub lightsource 3442. That is, the main light source 3441 and the sub lightsource 3442 are mounted on a long side of the light guiding plate 342 ina row, and they may be mounted on the opposing side.

Due to such a structure, in FIG. 19A and FIG. 19B, the LEDs L1 to L5 ofthe main light source 3441 and the sub light source 3442 are arranged atany one side of the LC panel 300, which is divided into a main displaypart 301 and a sub display part 302. That is, the LEDs L1 to L4 of themain light source 3441 are arranged at one side of the main display part301, having regular intervals therebetween, while the LED L5 of the sublight source 3442 is arranged at one side of the sub display part 302.This arrangement enables the light to be supplied to the LCDefficiently. In FIG. 19A and FIG. 19B, the main light source 3441 andthe sub light source 3442 are at the right of the LCD panel 300, butthey may be at the left.

A difference between FIG. 19A and FIG. 19B is the connection state ofthe LEDs. Similar to FIG. 17A and FIG. 17B, the LEDs L1 to L4 of FIG.19A are connected to each other in series, while the LEDs L1 to L4 ofFIG. 19B are connected to each other in parallel.

The operation of the main light source 3441 and the sub light source3442 is the same as the operation previously illustrated with referenceto FIG. 1 and FIGS. 17A-17B.

According to embodiments of the present invention, the display region ofthe LCD panel is divided into a main display part and a sub displaypart, and separate light sources are provided at each display part inorder to selectively operate the corresponding light source, accordingto the operation state of each display part. In this structure, it ispossible to selectively drive a portion of the entire light sources,when necessary images must be displayed in only a corresponding displaypart. Accordingly, power consumption by the light sources is reduced, sothat total power consumption of the display device is also reduced.

Although the illustrative embodiments have been described herein withreference to the accompanying drawings, it is to be understood that thepresent invention is not limited to those precise embodiments, and thatvarious other changes and modifications may be affected therein by oneof ordinary skill in the related art without departing from the scope orspirit of the invention. All such changes and modifications are intendedto be included within the scope of the invention as defined by theappended claims.

1. A liquid crystal display device, comprising: a low-resolution area;and a high-resolution area, wherein a pixel formed in the low-resolutionarea is larger than a pixel formed in the high-resolution area, and atleast a part of the low-resolution area exhibits only one color.
 2. Theliquid crystal display device of claim 1, wherein a pixel formed in thelow-resolution area is about three times as large as a pixel formed inthe high-resolution area.
 3. The liquid crystal display device of claim2, wherein a matrix of pixels formed in the low-resolution areacorresponds to a matrix of pixel groups formed in the high-resolutionarea, each pixel group consisting of red, green and blue pixels andbeing represented as a dot in the high-resolution area.
 4. The liquidcrystal display device of claim 3, wherein the data lines for supplyingimage signals to green pixels of the high-resolution area extend up tothe low-resolution area.
 5. The liquid crystal display device of claim1, wherein the low-resolution area exhibits white and black.
 6. Theliquid crystal display device of claim 1, wherein a plurality ofmonochrome areas, each exhibiting only one color, are included in thelow-resolution area, and each monochrome area exhibits a different colorfrom the other areas.
 7. The liquid crystal display device of claim 6,wherein at least one of the monochrome areas is comprised of pixels thateach have two kinds of color filters.